I need a help understand the operations dependency in this scenario

[mohammdsss1]

I need to maintain the value updates of one variable across my app, so let's assume I have this variable called number of type Int.

I created an operation called SerialOperation which responsible for incrementing number by one, the other operation called DataPrepOperation will wait (dependency on SerialOperation) for that operation to finish in order to use it. I also created PSBlockOperation that works as an adapter to ensure the transferring of that value between these two operations.

This design of operations was inspired by this post here.

My problem is that the operation called DataPrepOperation is always having the wrong value, for example: if I created three SerialOperation and another three DataPrepOperation then all DataPrepOperation will have the same last value. I don't understand what is the case here.

I attached the project for more.
AdapterOperation.zip